Boot up time

I've read a few posts commenting on performance, or lack thereof, of the Pi. I am using a SanDisk Extreme III (20MB/s) 4GB card in mine and have been pleasantly surprised by the performance of my Pi. It boots Debian (debian6-19-04-2012) to the login prompt in 22 seconds and the GUI takes another 14 seconds after that. Not too shabby.

I am wondering what sort of boot times other folks are seeing and what SD cards are you using?

I don't think anyone has reported anything close to 20 MB/sec on a SD card when used in the R-Pi. It would be interesting to know what your actual R/W speeds are, if you'd care to post some benchmark results using dd or anything else.

jbeale wrote:I don't think anyone has reported anything close to 20 MB/sec on a SD card when used in the R-Pi. It would be interesting to know what your actual R/W speeds are, if you'd care to post some benchmark results using dd or anything else.

jbeale wrote:I don't think anyone has reported anything close to 20 MB/sec on a SD card when used in the R-Pi. It would be interesting to know what your actual R/W speeds are, if you'd care to post some benchmark results using dd or anything else.

First login is slow. But subsequent logins, with nothing plugged into USB, just HDMI, ethernet and power I get login prompt at about 24 seconds with Debian on a 2 gig Sandisk ultra. What slowed it down a large amount (45s or more) was when I changed the keyboard settings from gb to us to go with my wireless us keyboard (changed it back now).

I have a Sandisk ultra 8 gig card I bought recently (2 gig is an old one) which I haven't been able to get running with either Arch or Debian.

AllegroMan wrote:I am wondering what sort of boot times other folks are seeing and what SD cards are you using?

login prompt in 10 seconds from poweron. Heavily modified version of Arch with all of the unnecesary starts-on-boot rubbish disabled.

At this point the Pi doesn't run it's sdcard interface at anywhere near maximum, the highest sequential read I've been able to get is around 5MB/s with a card that is capable of more in a different sdcard reader. So unless you have a really slow card or one that's deliberately optimised for a different usage pattern then the card itself is unlikely to be the limiting factor. It's way more likely to be the distro running all sorts of unnecessary bloat on boot.

I don't think anyone has reported anything close to 20 MB/sec on a SD card when used in the R-Pi. It would be interesting to know what your actual R/W speeds are, if you'd care to post some benchmark results using dd or anything else.

I used:sudo dd bs=1M count=128 if=/dev/zero of=~/test conv=fdatasync

and got 4.3 MB/sec, which is less than 25% of what the card is capable of.

Swapping that last parameter for oflag=dsync, so it syncs every 1M block (eliminating all write-caching) gives 4.0 MB/sec.

What is the limiting factor here; is it hardware level, or can optimisations be made at the OS level to speed up SD card I/O?

I have now also got a 16GB SanDisk Extreme 45MB/sec card working in the Pi. This required a firmware update as initially it gave interrupt timeout errors. In the Pi however this card is slower than the 4GB card!

Also the latest firmware has issues with my display. My monitor is actually a TV that has a 1680x1050 resolution but will accept a full 1080P signal and does a decent job of sampling it down to 1680x1050.

The Pi however was chopping off the leftmost and rightmost few characters of the display, so I had created a config.txt to put the display in 720p mode. With the new firmware this no longer works - I get no video (although I can log in "blind" and type shutdown and restart with a composite cable connected instead). With no config.txt the default 1080p mode works but is back to chopping off the characters.

Seems I'm best off with the 4GB card, original firmware and 720p video.

@dom thanks for that. I did try that first with the original firmware but it didn't seem to move the display at all. Your post prompted me to persevere and with the new firmware it does reposition the display.

So I can use the 16GB card now, but the only working mode is CEA mode 5 1920x1080 interlaced. Other modes boot, but the display is blank. Strangely, tvservice reports the only DMT mode supported is 640x480. I would have liked to have selected the native panel res of 1680 x 1050.

AllegroMan wrote:I've read a few posts commenting on performance, or lack thereof, of the Pi. I am using a SanDisk Extreme III (20MB/s) 4GB card in mine and have been pleasantly surprised by the performance of my Pi. It boots Debian (debian6-19-04-2012) to the login prompt in 22 seconds and the GUI takes another 14 seconds after that. Not too shabby.

I am wondering what sort of boot times other folks are seeing and what SD cards are you using?

I get just under 20sec (19.8s after averaging the times for 5 power ups) with a SanDisk Ultra (30Mb/s) Class 6 8Gb card from Costco. I'm using stock Debian (debian6-19-04-2012) but you do need the new kernal.img and start.elf files from github otherwise this particular card won't work.

I get a Debian start-up time of 2 min 27 sec but the majority of that is 'Activating lvm and md swap'.

Before I set up a swapfile on the SD card, start-up was much faster (~ same kinds of time as others are reporting).

I have a 1 GB swapfile. I know swap is never fast and there is debate about whether it might shorten SD card life. However, these seem generally less disastrous than running out of address space. Just running a couple of simple things, a modest amount of swap space does occasionally get used, and I assume things would have got weird without it.

Incidentally - what is the maximum sensible amount of swap, on this 32-bit system? I assume either 1.5 GB or 3.5 GB? Apologies, this is probably a fairly generic Linux question but I couldn't find the answer.

DanielBarker wrote:I get a Debian start-up time of 2 min 27 sec but the majority of that is 'Activating lvm and md swap'.

Before I set up a swapfile on the SD card, start-up was much faster (~ same kinds of time as others are reporting).

I have a 1 GB swapfile. I know swap is never fast and there is debate about whether it might shorten SD card life. However, these seem generally less disastrous than running out of address space. Just running a couple of simple things, a modest amount of swap space does occasionally get used, and I assume things would have got weird without it.

Incidentally - what is the maximum sensible amount of swap, on this 32-bit system? I assume either 1.5 GB or 3.5 GB? Apologies, this is probably a fairly generic Linux question but I couldn't find the answer.

Thanks,

Daniel Barker

I'm also getting a very slow "Activiating Swap"... It can take up to 115 seconds... Though on some occasions it can take 5seconds... Does anyone know the reason for the delay?

I've been amazed at how fast my Pi boots up. I'm running Debian with LXDE on a cheap 4-year-old Transcend 4gb SD card. It doesn't say what class it is on the label, so I presume it's Class 4, but it does say "133X", implying it's fast. Anyway, the total boot time (including loading LXDE) is 37 seconds. Is this a record for Debian + LXDE?

DanielBarker wrote:Incidentally - what is the maximum sensible amount of swap, on this 32-bit system? I assume either 1.5 GB or 3.5 GB? Apologies, this is probably a fairly generic Linux question but I couldn't find the answer.

Optimum swap file size is entirely dependent on how the system is being used, memory usage over time of the applications/services running, file I/O sizes and usage patterns, etc. Twice RAM size (512MB, in this case) is usually a good starting point, and swap size can be adjusted up or down to see what effect, if any, that has. Generally, the larger the number and smaller the memory footprint of executables, the larger the swap file size should be, but, again, this is one of those things where knowledge about actual usage is key. As with everything about the PI, feel free to experiment - you can't hurt anything!

BTW, if you're really serious about using swap, you're much better off moving it to an external USB hard disk drive - the interface is faster than the SD card slot, the hard disk RAM buffer will help get reads/writes off the bus the fastest, and you won't have to worry about wearing out the SD card over the long run.

The best things in life aren't things ... but, a Pi comes pretty darned close! "Education is not the filling of a pail, but the lighting of a fire." -- W.B. YeatsIn theory, theory & practice are the same - in practice, they aren't!!!

Jim Manley wrote:BTW, if you're really serious about using swap, you're much better off moving it to an external USB hard disk drive - the interface is faster than the SD card slot, the hard disk RAM buffer will help get reads/writes off the bus the fastest, and you won't have to worry about wearing out the SD card over the long run.

I get about 25MB/s on a USB disk (sequential). With the latest changes at least higher end SD cards should be able to match that or come close.